1. Field of the Invention
The invention relates to a method and a plant for the treatment of waste water, particularly that which contains calcium chloride and which accumulates, for instance, in washers for gas purification or in plants for desalting of mixtures of solids.
2. Description of the Prior Art
Gas purification washers are used, for example, for desulfurization of flue gases from steam generators which are heated with fossil fuels. In these washers, waste water containing calcium chloride and other chlorides accumulates. The chloride concentration depends on the chloride content of the fuels and on the method of operation of the gas purification plant.
Waste water which contains chloride can also accumulate during the extraction of chloride-containing mixtures of solids which originate from plants for dry gas purification with alkali compounds or alkaline earth compounds.
The large amounts of chloride-containing waste water which accumulate lead to a considerable stress of the main canal, particularly in large plants. Even when the waste waters are vaporized or spray dried, the calcium chloride salt obtained has only limited industrial use, resulting in large amounts being stored in deposit areas. For this purpose, the calcium chloride salts must be packed in a permanently waterproof way due to their hygroscopic behavior and their water solubility and this incurs considerable expenses.